Force discriminating mechanism



J1me 1964 J. DE SABLA ETAL 3,136,252

FORCE DISCRIMINATING MECHANISM Filed Aug. 7, 1962 YNVENTORS LOUIS J. de SABLA WILLIAM J. DONAHUE I ATTY.

United States Patent 3,136,252 FORCE DISCRIMINATING MECHANISM Louis J. de Sabla, Silver Spring, and William J. Donahue,

Takoma Park, Md., assignors to the United States of America as represented by the Secretary of the Navy Filed Aug. 7, 1962, Ser. No. 215,469 9 Claims. (Cl. 102-78) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a safety mechanism for a projectile fuze and more particularly to a mechanism for effectively restraining the arming of a fuze when there is abnormal rotation of the projectile.

In the field of projectile fuze arming, it has been the general practice to employ various types of safety mechanisms of the inertial or centrifugal type to prevent premature initiation of the explosive charge in a projectile. None of these prior art mechanisms, however, has been capable of functioning in a force discriminating manner, that is, none of them has been constructed to prevent the arming of the detonating device or fuze in a projectile when it is subjected to abnormal or inadvertent rotation, while allowing the arming of the fuze when there is normal linear motion of the projectile.

The general purpose of this invention, therefore, is to provide a fuze safety mechanism which embraces all the advantages of similarly employed prior art mechanisms and possesses none of the aforedescribed disadvantages. To attain this, the present invention contemplates a novel safety mechanism of the centrifugal type which will prevent arming of a fuze when the projectile is subjected to abnormal rotation.

It is therefore an object of this invention to provide a new and improved safety mechanism for a projectile fuze or detonating device.

Another object is to provide a force discriminating mechanism in a projectile fuze for preventing arming of the fuze under predetermined conditions of rotation of the projectile.

A further object is the provision of a safety mechanism for a projectile fuze for preventing arming of the fuze when the projectile is subjected to abnormal rotation, while allowing fuze arming when there is normal linear motion of the projectile.

Still another object is to provide a safety mechanism for a projectile fuze or the like which is simple, compact and reliable in operation.

Other objects and various further features of novelty and invention will be apparent to those skilled in the art from a reading of the following specification and claims in conjunction with the accompanying drawing, which shows, for illustrative purposes only, one form of the invention and in which:

FIG. 1 is an elevational view, partly in section, of one embodiment of the invention;

FIG. 2 is a plan view of a portion of the apparatus shown in FIG. 1; and

FIG. 3 is an enlarged end view, partly in section, of a portion of the apparatus shown in FIG. 1.

In the illustrated example of the invention, and referring first to FIG. 1, there is shown a housing 11 for a fuze that is externally threaded at 12 so as to be mounted within a projectile head. The housing 11 has an open end 13 that is interiorly threaded to receive therewithin an exteriorly threaded cap 14 for the closure thereof. A guide tube 15 is rigidly mounted within the fuze housing 11 and is provided with longitudinally extending slots 16 3,136,252 Patented June 9, 1964 and 17 on opposite sides thereof. Mounted within the guide tube 15 is a lever member 18 comprising two halves 19 and 20 which are rigidly joined together by a center pin 22, as shown in FIGS. 2 and 3.

Referring now to FIGS. 1 through 3, pins 23 and 24 are rigidly mounted on the lever halves 19 and 20, respectively, and the pins are pivotally mounted within the longitudinal slots 16 and 17, respectively, formed in the tube. A retaining ring 21 is mounted on the guide tube 15 adjacent the protruding portions of the pivot pins 23 and 24, thereby allowing rotation of the pins and limiting the axial movement thereof. The retaining ring 21 may be welded to the guide tube 15 or may be rigidly attached thereto by other similar methods.

A cylindrical member 25 is rigidly attached to the pin 24 and is slotted at 26 to slideably receive the end portion 27 of a locking tab 28. The tab 28 is secured to the cylindrical member 25 by rivets 29 passing through the member 25 and the end portion 27. In the assembled position, as shown in FIG. 1, the locking tab 28 is located within a slot 31 in the rotor 32 to prevent substantial rotation of the rotor which is part of the acceleration-responsive arming mechanism of the fuze. In order to arm the fuze, the rotor 32, as shown in FIG. 1, must rotate in a clockwise direction approximately 60 from the assembled position shown in FIG. 1. Therefore, when the locking tab 28 is within the rotor slot 31, this will prevent arming of the fuze.

Mounting pins 33 and 34 are retained in holes 35 and 36, respectively, in the lever halves 19 and 20. The wire rod 37 is pivotally mounted at one end on the mounting pin 33, and at the other end thereof the rod is provided with a circular loop 38 which is received in a groove 39 formed in the spherical weight 41. A second wire rod 42, shorter than the rod 37, is pivotally mounted at one end on the mounting pin 34, and is provided with a circular loop 43 at the other end thereof which is received in a groove 44 formed in the spherical weight 45. It is noted that the weight 41 has a central bore 46 therethrough to compensate for the longer length of the wire rod 37. Therefore, the total weight of the wire rod 37 and the spherical weight 41 is equal to the total weight of the shorter rod 42 and the spherical weight 45.

In operation, when there is normal linear acceleration of the projectile head, the force of the spherical weight 45, shorter wire rod 42 and the locking-tab 28 is greater than the force of the longer rod 37 and the spherical weight 41 upon the lever member 18. This will result in a clockwise rotation of the lever member 18 to the dotted line position shown in FIG. 1, with a resulting clockwise rotation of the locking tab 28 to its dotted line position. Accordingly, the rotor 32 will be free to rotate and the acceleration arming mechanism will be capable of arming the fuze.

On the other hand, if there is abnormal or inadvertent rotation of the projectile head, such as end-over-end tumble, since the spherical weights 41 and 45 are both located rearwardly of the center of gravity of the projectile head and at significantly different distances therefrom, a greater centrifugal force will be exerted upon the spherical weight 41, since it is farther from the projectile head center of gravity, which will cause the lever member 18 to be retained in the assembled position shown by the solid lines in FIG. 1. Since the locking tab 28 is retained within the slot 31 in the rotor 32, the rotor is prevented from rotating in a clockwise direction and the acceleration arming mechanism is prevented from arming the fuze. Thus, a force discriminating mechanism is provided by this invention which wll allow acceleration-arming of a projectile fuze only when the projectile head is subjected to normal linear acceleration.

It is noted that although many alternate constructions of the present invention are possible, a few in particular may deserve mention. For example, a system of two racks with a pinion as a center fulcrum and heavy ends on the extremes ofthe racks could be readily employed; the construction of the lever member could be varied to a large degree; and the shape of the other components of the subject construction, such as the locking tab, the rotor slot, and the shape of the weights and guide tube, could be widely varied without departing from the scope of the invention.

While the invention has been described in detail for the illustrated form shown, it will be understood that many other modifications may be made within the scope of the invention as defined in the appended claims.

What is claimed is:

1. Safety apparatus for a fuze in the head of a projectile comprising means for arming the fuze in response to linear acceleration of the projectile, and means for preventing operation of said arming means when the projectile is subjected to abnormal or inadvertent end-overend rotation, whereby the fuze will be armed only when the projectile is subjected to normal linear acceleration.

2. Force discriminating apparatus for a fuze in the head of a projectile comprising means for arming the fuze in response to linear acceleration of the projectile, locking means for preventing operation of said arming means when the projectile is subjected to abnormal or inadvertent end-over-end rotation, and means for releasing said locking means and allowing operation of said arming means only when the projectile is subjected to normal linear acceleration.

3. The apparatus of claim 2 wherein said arming means comprises a rotor mounted within the fuze and having a I therethrough, whereby the weight of said longer rod and slot therein.

4. The apparatus of claim 3 wherein said locking means comprises a lever pivotally mounted within the fuze and having a locking tab thereon which normally extends into said rotor slot to prevent the rotation of said rotor necessary for the arming of the fuze.

S. The apparatus of claim 4 wherein said releasing means comprises a first rod pivotally mounted at one end thereof on said lever on one side of the lever pivot point #slot therein.

-means comprises a tab whch normally extends into said pivot point and having a second weight mounted on the other end thereof, said rods extending in opposite directions from the lever, said first and second weights being on the same side of and at different distances from the center of gravity of the projectile head, and means to guide the movement of said weights.

6. Safety apparatus for a fuze mounted in the head of a projectile comprising a supporting tube rigidly mounted within the fuze, a lever member pivotally mounted within said tube, a pair of opposing connecting rods within said tube pivotally mounted apart on said lever adjacent the outer edge thereof on opposite sides of the lever pivot point and extending in opposite directions from said lever,

said rods being of different lengths and each having a spherical weight mounted on the free end thereof, said Weights being freely movable within said tube and being on the same side of and at different distances from the 'center of gravity of the projectile head, means for arming the fuze in response to linear acceleration of the projectile, and locking means rigidly mounted on said lever member for preventing operation of said arming means when saidweights aresubjected to different acceleration forces respectively and resulting from abnormal or inadvertent end-over-end rotation of the projectile head,

whereby the fuze will be armed only when the projectile 8. The apparatus of claim 7 wherein said locking rotor slot to prevent rotation of said rotor and therefore "operation of said arming means.

9. The apparatus of claim 6 wherein the spherical weight mounted on the longer of said rods has a bore said weight mounted thereon is equal to the weight of the shorter rod and the weight mounted thereon.

References Cited in the file of this patent UNITED STATES PATENTS 2,448,228 McCaslin et al Aug. 31, 1948 2,801,589- Meek et a1 Aug. 6, 1957 2,943,573 Graser July 5, 1960 

1. SAFETY APPARATUS FOR A FUZE IN THE HEAD OF A PROJECTILE COMPRISING MEANS FOR ARMING THE FUZE IN RESPONSE TO LINEAR ACCELERATION OF THE PROJECTILE, AND MEANS FOR PREVENTING OPERATION OF SAID ARMING MEANS WHEN THE PROJECTILE IS SUBJECTED TO ABNORMAL OR INADVERTENT END-OVEREND ROTATION, WHEREBY THE FUZE WILL BE ARMED ONLY WHEN THE PROJECTILE IS SUBJECTED TO NORMAL LINEAR ACCELERATION. 